Well for the warlord specifically there is tons of stuff out there to parse through.It people really were able to create it in a well enough done manor to be majority acceptable, there wouldn't be a lack.
Simple market econ: if there's demand, and low enough risk, it would be done. (Has been, last I heard, just not well.)
Since there isn't a credible one, that implies either a lack of skill sufficient to the task, insufficient reward for doing it, excessive risk, and/or no demand. Possibly all three.
DM's Guild removes risks save for the time sink and public embarrassment.
Insufficient reward? Possibly, but there are a lot of things going up despite the VERY low return on time.
There is at least SOME demand...
So, it it's wanted, the only real bottlenecks are desirous customers finding it amidst the flurry of product and having the skill to do the product in the first place.
Which is part of the problem. First you gotta soft through all that's available to get what you like.
Then you have to present one or two options to your DM and hope they accept it.
And that's kind of the issue. Simple DIYs like races, items, weapons, groups, clans, backgrounds and lore bits are easy to present and rejigger to a DM/GM's liking or acceptance. Complex DIY like classes, subclasses, subsystems, magic systems, disciplines, and variant rule changes have different approaches, desires, balances, as well as intended and unintended consequences that any DM who simply says yes with a glance is walking into a world of hurt. The amount of drafts, feedback, playtest, questioning, and redesign needed to even make one for constant home use is more than most expect. So many end up with people relying on others with the expertise on doing this and hoping one of said people opt to it.
For example, I have an acceptable version of my Paragon class for 3 editions of D&D for when I DM.
I sure don't have a Paragon to present to any other DM or GM. And certainly haven't done enough to sell it.